Kayaks, along with canoes and other lightweight, personal watercraft are commonly used for recreational travel on rivers, lakes and oceans. They are also used for fishing and hunting. This invention comprises various improvements that advance the design concepts introduced in U.S. Pat. No. 8,316,788, issued Nov. 27, 2012 to the present inventor, which describes a method and apparatus to build origami-based, folding kayaks out of lightweight corrugated plastic sheet material. A salient advantage of that design is that a single sheet forms the kayak and it may be refolded into a case structure that serves as a self-made container for the watercraft and associated gear when it is in its folded (knockdown) disposition.
Kayaks typically have a rigid rim around the cockpit opening, called a “coaming”. This reinforces the structure of the kayak at its weakest point (where a large hole is cut out of the deck, for the user to extend the lower body into and sit inside). Additionally, it provides support for the user when entering and exiting the kayak; normally the user lifts herself out of the kayak with her arms, by placing all of her weight on the coaming. Due to the structural weakness introduced by the cockpit opening, watercraft designers have tended to make this opening as small as is practical and possible for the kayak user. (A small cockpit opening also has the advantage of enabling the use of a waterproof skirt worn about the kayak user and fastened across the opening to prevent water washing into the cockpit.)
The small cockpit opening can interfere with the kayaker enjoying some of the ancillary pleasures associated with watercraft, such as fishing, boating with pets (particularly dogs), and the like. Also, it can be rather confining and limiting for the boater, in terms of bending the legs for positional variety, stretching and flexing the legs, and the like. In addition, below-deck storage is difficult to access, and it is often difficult to access stored gear without landing or docking and exiting the cockpit.
There is of course a tradeoff in providing a spacious cockpit than enables more freedom of movement of the boater, and that is the increased susceptibility to taking on water from waves and rain. Thus a watercraft with a spacious cockpit opening is intended more for calm waters that will not inundate the craft. And the prior art exemplifies a further tradeoff: the decreased stiffness and strength of the midship portion of the watercraft as more spacious cockpit space is designed into the craft.